[PATCH 1/3] workqueue: free worker earlier in worker_thread()

[Lai Jiangshan <laijs@cn.fujitsu.com>]

When @worker is set %WORKER_DIE, it is moved out from
idle_list&idr, no one can access it excepct kthread_data().

And in worker_thread, its task is clearred %PF_WQ_WORKER,
no one can access the @worker via kthread_data(),
we can safely free it.

Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
---
 kernel/workqueue.c |    3 ++-
 1 files changed, 2 insertions(+), 1 deletions(-)

diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index 783d5f2..fc05700 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -1862,7 +1862,6 @@ static void destroy_worker(struct worker *worker)
 
 	kthread_stop(worker->task);
 	put_task_struct(worker->task);
-	kfree(worker);
 
 	spin_lock_irq(&pool->lock);
 }
@@ -2297,6 +2296,8 @@ woke_up:
 		spin_unlock_irq(&pool->lock);
 		WARN_ON_ONCE(!list_empty(&worker->entry));
 		worker->task->flags &= ~PF_WQ_WORKER;
+		/* No one can access to @worker now, free it. */
+		kfree(worker);
 		return 0;
 	}
 
-- 
1.7.7.6